Ariadne auf Naxos

Strauss's Ariadne auf Naxos is essentially an opera about opera: it explores the gap between backstage chaos and on-stage glory. Life, as we know, can sometimes imitate art. This revival of Christof Loy's 2002 staging has already had its fair share of offstage vicissitudes, thanks to revelations, a few months ago, that the Royal Opera had removed Deborah Voigt from the production on account of her weight and replaced her with the slimmer Anne Schwanewilms.

Unfortunately, the compensatory on-stage glories don't always materialise. This is one of those awkward evenings that simply doesn't cohere and Schwanewilms, sadly, is one of its drawbacks. She made a sensational UK debut as Ariadne in concert at the Barbican four years ago, and anyone who heard that remarkable performance cannot fail to be struck by her subsequent decline. The tone has lost much of its former lustre. On opening night, the climax of Ariadne's great lament brought with it severe pitch problems, and self-dramatisation has replaced genuine intensity.

Loy may well be responsible for the latter, for his production is an ill-focused affair. It bears out the common criticism that the work lacks unity by curiously making the opera which the characters perform different from the one we have watched them prepare. Some nice touches - a hefty emphasis on the relationship between art and patronage, Zerbinetta being cruelly ditched by Harlequin at the end - don't make up for lengthy stretches of theatrical confusion, and the principal pleasure here derives from Colin Davis's reflective, lyrical conducting and a handful of striking individual performances.

Susan Graham is the eloquent, neurotic Composer. Diana Damrau, all shuddering trills and cleavage, is a fantastic Zerbinetta, generating a formidable erotic charge with Grant Doyle's punkish, fatigues-clad Harlequin. The evening is well worth it for the pair of them, whatever its inequalities elsewhere.